Clownfish

Alex Re: [00:00:00] Hello, welcome to On Wildlife. I'm your host, Alex Re. On this podcast, we bring the wild to you. We take you on a journey into the life of a different animal every month, and I guarantee you you're gonna come out of here knowing more about your favorite animal than you did before. Today, we're covering a really colorful animal that you might recognize from a couple of movies.

These tropical fish can be found swimming around coral reefs, and they have an intricate relationship with another ocean animal. So try not to laugh as we head under the sea to talk about clownfish.

There are about 30 species of clownfish, all belonging to the genus Amphiprion, and they're in the Pomacentridae family, which also includes [00:01:00] damselfish. They get the name clownfish because the interesting patterns and vibrant colors of their bodies look similar to a clown costume. One clownfish species that you might recognize is Amphiprion ocellaris, also known as the common clownfish.

They're a bright orange color with large white stripes that encircle their body. Most species do have some orange coloration, but there are some species, like the whitesnout anemonefish, that are black with one white stripe and a white tail. Clownfish are strictly saltwater fish, and they prefer to swim in warmer waters, so you won't find them in the deep ocean.

They live in coral reefs, where the water is shallow enough for sunlight to reach, and they have an extremely important relationship with another animal in these reefs, but we'll get to that a little later. Clownfish are native to the Pacific and Indian Oceans, living along the east coast of Asia and all the way down [00:02:00] to the northern coast of Australia.

Clownfish are pretty small fish in general. The smallest clownfish species can be as small as four inches in length, while the largest only gets to be around six and a half inches long. They can also live for about 10 years in the wild. Clownfish are omnivores, meaning that they eat both plant and animal matter.

They'll eat algae, plankton, and small crustaceans, like shrimp. And although it doesn't look like it, they actually have teeth to help them hold onto their prey and to defend themselves against predators. What's really crazy is that they also have teeth inside of their throats, called pharyngeal teeth.

These teeth are used to help them break down their food. But how do they catch their prey? Well, here's where the interesting relationship with another animal comes into play, but let's save it for after the break.[00:03:00]

Just a reminder that we now have a Patreon. If you like the podcast and wanna support us, you should check us out at patreon.com/onwildlife. If you're a paid member, you'll receive early releases to our episodes, exclusive Q&A episodes, and more. Okay, let's get back to the episode. Clownfish have a symbiotic relationship with sea anemones.

This just means that they interact with each other in their native habitats. This is why all clownfish species live in shallow, warm waters where the light penetrates to the bottom of the ocean. That's where sea anemones thrive. Sea anemones have tentacles that can give a painful sting to anything that comes in contact with them.

They contain cells called cnidocytes. When these cnidocytes are touched, they release a microscopic harpoon that shoots out, causing a stinging sensation. [00:04:00] In addition to that, the harpoons have venom inside of them that can cause pain and can even kill different fish species. But clownfish actually live inside of the tentacles of the sea anemone and don't get stung.

This is because they have a layer of mucus surrounding their skin that deters the tentacles from being triggered. Research shows that some species are born with this immunity to anemone stings, but others actually have to acclimate themselves over time. Clownfish that are not immune will repeatedly rub themselves against the tentacles of the anemone.

When they first do this, they'll be stung, but after doing this enough times, they'll eventually become immune to the stings. So why do the clownfish go through all the trouble of acclimating to the stings of the sea anemone? Well, there are actually a lot of reasons. They have a mutualistic, symbiotic relationship with the sea anemone, meaning that they both benefit from this interaction.

The main reasons [00:05:00] that clownfish rely on sea anemones is because they offer a way to get food, and they also provide protection against predators. One strategy that clownfish use to get food is by luring other fish into the tentacles of the sea anemone. They'll follow the clownfish, thinking that they're getting an easy meal, but instead they'll be killed by the tentacles.

This also benefits the sea anemone, because the anemone will eat most of the fish, and the clownfish will eat the scraps left over And clownfish have tons of predators lurking around their habitat, like lionfish and eels, so the protection that sea anemones offer is invaluable. This is especially important considering that clownfish aren't great swimmers, so they definitely won't be able to outmaneuver their larger and quicker predators.

Another extremely useful trait that clownfish use to avoid predators is their coloration. As I mentioned before, some clownfish species are bright [00:06:00] orange with white stripes. A study conducted in 2018 found that clownfish species with more stripes tended to live inside of sea anemone species that weren't very venomous, and those that lived in anemone species that were more venomous had less stripes.

This told the scientists a few things about how clownfish use their colors to their advantage. Their white stripes are helpful in blending in with sea anemones, so this strategy is used when the anemone isn't as dangerous to predators. The bright orange with less stripes, on the other hand, makes clownfish stand out more, and that's the point.

The bright coloration is used as a warning to other animals that they're dangerous, kind of like how a poison dart frog has bright colors to warn other animals that they shouldn't be eaten. What's interesting is that not only do sea anemones protect clownfish, but clownfish return the favor by protecting the sea anemone from their predators.

There are certain fish that [00:07:00] eat sea anemones, like the raccoon butterflyfish, and clownfish are able to scare them away from the anemones. Clownfish are extremely territorial when it comes to their anemones, and they've even been known to bite people swimming around their homes. Studies have also shown that anemones can actually grow more quickly when clownfish are using them as a home because they increase the amount of oxygen that anemones get by swimming back and forth through them.

And another reason for the increased growth is that the anemone is able to take in nutrients from the waste of clownfish. So in more ways than one, clownfish and sea anemones are the textbook example of a mutualistic relationship. Okay, we've spent a lot of time talking about the clownfish's relationship with the sea anemone, but what about clownfish's relationships with each other?

I think there are some interesting facts that are gonna really surprise you, so let's talk about it after the break.[00:08:00]

Time for today's trivia question. What is the maximum distance that a kangaroo can jump? 15 feet, 25 feet, 35 feet, or 45 feet?

The answer is 45 feet. Aside from their relationship with the sea anemone, relationships between clownfish are very important because clownfish are social animals. They communicate with each other using clicking sounds, and a group of clownfish is either called a circus or a queue They have a really interesting social hierarchy where the group is made up of a bunch of males with one dominant female.

Underneath the dominant female in the hierarchy is the dominant male, [00:09:00] and something you might not know about clownfish is that they're actually all born as males. The largest male in the group becomes a female. This change starts in the brain, which causes them to start producing different hormones and slow the production of other hormones.

Once this happens, it can take a few weeks to a few years for them to fully make this change. When the female in the group dies, then the dominant male will change its sex to female and become the dominant female. But once a male changes to a female, he cannot change back. The dominant female limits the amount of food that the others can eat so that she remains the largest in the group.

The dominant male also limits what other males can eat, and this is actually a lot more common across species than you'd think, as a ton of different fish species living in coral reef ecosystems are able to change their sex. Once it's time to [00:10:00] reproduce, the female can lay up to 1,500 eggs at one time.

She lays them on a flat surface, usually underneath or near the host sea anemone. And after she lays the eggs, the dominant male fertilizes them. The male and female will both guard the eggs, but the male will also use his fins to circulate water on the eggs to make sure that they're getting enough oxygen.

If any of the eggs get damaged, the male will eat them. It only takes about 10 days for the eggs to hatch, and once they hatch, they're on their own. So Marlin probably wouldn't go looking for Nemo if Finding Nemo took place in real life. So clownfish have really interesting lives, and we've talked about the relationships that they have with each other and with anemones, and that's one of the reasons why they're so important to the ecosystems that they live in.

Clownfish impact the growth of sea anemones, which control populations of other organisms like [00:11:00] plankton and small fish. This is extremely important because if plankton become overpopulated, it can result in an algal bloom, which can decrease the amount of oxygen in the specific area where they're blooming, and that can cause a huge amount of deaths in that ecosystem.

Sea anemones also help to recycle important nutrients throughout their environment. But the clownfish's reliance on sea anemones is also why their populations are in danger. Because of climate change, the temperature of the world's oceans is increasing. This starts to make it unsuitable for sea anemones to live in.

Just like coral, sea anemones have a symbiotic relationship with microscopic algae, which provide them nutrients. When the ocean temperature increases, the algae leave, and the anemones are no longer getting those nutrients. Another problem that sea anemones are facing is actually pesticides. A study conducted by [00:12:00] Oregon State University found that specific pesticides can impact the sea anemone's ability to develop their reproductive organs.

These specific pesticides that were tested have already been found in our oceans. When we spray our crops with pesticides and it rains, the water runoff carrying these pesticides ends up in our oceans. So when the sea anemone population goes down because of these factors, that has a major impact on clownfish because they rely on anemones for survival.

Clownfish also face problems such as overfishing and capture from the wild to be sold into captivity. They're one of the most popular exotic fish on the market because of their beautiful colors. Clownfish populations are on the decline, so it's important that we focus on their conservation, and we can't help the populations of clownfish without the conservation of oceans as a whole.

So if you'd like to support organizations that help clownfish and ocean conservation, [00:13:00] you should check out Oceana, Coral Restoration Foundation, and Reef Renewal USA. Thank you so much for coming on this adventure with me as we explored the world of clownfish. You can find the sources that we used for this podcast and links to organizations that we reference at onwildlife.org.

You can also email us with any questions at onwildlife.podcast@gmail.com, and you can follow us on Instagram at on_wildlife or on TikTok at onwildlife. And don't forget to tune in next month for another awesome episode. And that's On Wildlife.